1. Field of the Invention
The present invention relates to an ink jet recording head which comprises an ink liquid path communicating with a discharging orifice for discharging an ink, and an energy generation means for generating energy utilized to discharge the ink from the discharging orifice, provided along the ink liquid path, a process for producing the ink jet recording head, and an ink jet recording apparatus, which comprises the ink jet recording head.
2. Related Background Art
An ink jet recording head generally comprises five orifices for discharging an ink, ink liquid paths provided for each of the five orifices and communicating with the five orifices, respectively, and an energy generating means for generating energy for discharging the ink, provided each at parts of the individual ink liquid paths. In most cases, one ink jet recording head is provided with a large number of discharging orifices and common liquid chamber to the individual ink liquid paths, which serves to stably supply the ink to the individual ink liquid paths As the energy generating means, a device for converting electric energy to discharge energy, for example, an electro-thermal converting element or a piezoelectric device, is used.
Typical processes for producing an ink jet recording head are as follows:
(1) A process which comprises providing a first base member provided with an energy generating means and a second base member composed of glass or metal, forming discharging orifices, in the second base member by processing means such as cutting or etching, ink liquid paths, a recess for forming a liquid chamber and a supplying hole communicating the liquid chamber with the outside, the positioning the energy generating means of the first base member to the ink liquid paths of the second base member, and bonding the second base member to the first base member by an adhesive.
(2) A process which comprises pasting a positive type, photosensitive resin dry film on a base member composed of, for example, glass and provided with an energy generating means, exposing the photosensitive dry film to light and developing the film by photolithography, thereby providing a solid layer with a pattern corresponding to discharging orifices, ink liquid paths and a liquid chamber on the base member, then applying a liquid curable material containing a curing agent on the solid layer and the base member to a desired thickness, leaving the applied base member at a desired temperature for a desired time, thereby curing the curable material, then cutting the base member at an orifices-forming position, thereby exposing the edge surface of the solid layer, and dipping the base member in a solution capable of dissolving the solid layer, thereby removing the solid layer from the base member by dissolution and forming the ink liquid paths and a space for the liquid chamber inside the base member (Japanese Patent Application Laid-Open No. 61-154947 corresponding to U.S. Pat. No. 4,657,631).
(3) A process which comprises pasting a photosensitive dry film on a first base member provided with an energy generating means, exposing the photosensitive dry film to light and developing the film, thereby forming a solid layer with a pattern corresponding to discharging orifices, ink liquid paths and a portion of a liquid chamber on the first base member, applying an active energy ray-curable material which can be cured with an active energy ray such as ultraviolet rays or electron beams, on the solid layer and the first base member to a desired thickness, providing a second base member capable of transmitting the active energy ray therethrough, provided with a recess for forming another portion of the liquid chamber and a supplying hole, pasting the second base member on the active energy ray-curable material so that the recess of the second base member can be provided at a position destined to form the liquid chamber, thereby forming a laminate, then masking the second base member so as to mask the portion destined to form the liquid chamber, irradiating the active energy ray-curable material with the active energy ray through the second base member, thereby curing the active energy-curable material, then cutting the laminate at an orifices-forming position, thereby exposing the edge surface of the solid layer, removing the solid layer and uncured active energy ray-curable material from the laminate by dissolution, thereby forming ink liquid paths and a space destined to form the liquid chamber inside the laminate (Japanese Patent Application Laid-Open No. 62-253457 corresponding to U.S. Pat. No. 5,030,317).
In the production of an ink jet recording head, the above-mentioned process (1) can provide a large liquid chamber suitable for high speed recording, but requires exact positioning of five energy generating means of the first base member to five ink liquid paths of the second base member before bonding of these two members, resulting in complication and higher cost of an apparatus for this purpose, unappropriateness for mass production and an increase in the product cost as problems. The above-mentioned process (2) requires no such exact positioning, but the volume of the liquid chamber is restricted by the thickness of the patterned solid layer and no larger liquid chamber can be formed. Furthermore, the process steps are so many and complicated as to require much time. Thus, the process is not appropriate for mass production, resulting in an increase in the product cost as a problem. The above-mentioned process (3) can provide a larger liquid chamber, because the recess for forming another portion of the liquid chamber can be made larger and requires no such exact positioning, but the process steps are so many and complicated as to require much time and the process is not appropriate for mass production, resulting in an increase in the product cost as a problem, as in the process (2).
To solve the problems, such a process has been proposed, which comprises providing a solid layer with a pattern corresponding to discharging orifices, ink liquid paths, and a portion of a liquid chamber on a base member provided with an energy generating means, forming the orifices, the ink liquid paths and the liquid chamber on the base member by integral molding of synthetic resin and then removing the solid layer by dissolution. In this case, the solid layer acts substantially as a portion of a mold for the integral molding, contributing to formation of the ink liquid paths as undercut parts. However, the ink jet recording head produced by the process still has such problems as peeling or separation of the integrally molded synthetic resin from the base member due to a difference in temperature between the production and the application or occurrences of print twisting or splashes due to cross-talk at the printing.